Conventionally, there is known a substrate liquid processing apparatus that performs a liquid process on a substrate such as a silicon wafer or a compound semiconductor wafer.
In the substrate liquid processing apparatus, a liquid process using plural kinds of processing liquids such as an acidic processing liquid, an alkaline processing liquid and an organic processing liquid may be performed. In such a case, the substrate liquid processing apparatus is equipped with a plurality of individual exhaust pipes corresponding to the processing liquids, respectively, and a switching unit configured to switch a discharge destination of an exhaust gas to one of the plurality of individual exhaust pipes (see Patent Document 1).
Patent Document 1: Japanese Patent Laid-open Publication No. 2013-033922
In the above-described prior art, however, there is still a room for improvement in that a pressure variation of a liquid processing unit, which might be accompanied by the switching of the gas exhaust, needs to be suppressed.